Scottish Environment Protection Agency (SEPA) Update on Dawn Homes Site Issues
Provided by SEPA Office Representative, Ayr Office to FCC Secretary
Run-Off in to SUDs pond.
The main problem is that not all of the run-off had been directed to the SUDs pond as it should have been. An element of run off which should have been discharging to the pond was in fact directed in another direction and discharging at another location. (Keppen Burn).
The drainage routes have now been changed and all of the run-off should be entering the pond.
In addition to this inspection of the site has revealed a number of other improvements that can be made which should help the situation:-
1. Additional ‘Up-hill’ drainage ditch.
Firstly a cut-off ditch will be constructed on the ‘uphill’ side of the site to intercept any clean water entering the site from the hill at the rear. This cut-off ditch will intercept any surface flow and will catch flow from land drains in the area and direct this clean water around the site to the Keppen Burn to prevent it from entering the site and being contaminated and then requiring to be treated. This will reduce the volume of water requiring treatment in the SUDs pond.
2. Redirect run-off from the bare slopes on each side of the access road.
There is a need to better manage the run-off from the area where the houses are currently being built. Currently the run-off flows over and scours out the bare earth; SEPA have instructed Dawn Homes to direct the water to flow across stone to reduce the amount of solids carried by the run-off to the pond and reduce the burden on the treatment system.
3. Bare Earth Bankings.
It has been agreed that the bare earth bankings will be seeded at the earliest opportunity. This seeding work will not be carried out when weather permits in January 2017, by means of ‘hydroseeding’. Hydroseeding is a technique where seed and mulch are mixed and applied by spraying the mixture on to the ground in the form a thick paste. This methodology protects the seed, should prevent wash off in all but the heaviest rainfall events and should encourage rapid germination and growth. The landscapers believe this will work this time of year.
4. Modifications to SUDs pond.
It has also been agreed that some modifications to the pond will be carried out to attempt to improve the treatment it provides. In this regard the pond will be sub-divided into two main sections by construction of a berm. In addition to this the contractor is considering the use of flocculating agents to assist the settlement in the pond if this proves necessary.
5. Regular SEPA inspections.
It has also been agreed that regular inspections of the burn and the discharge from the pond will be made and appropriate action taken as necessary. Visually the water in the pond looks very dirty. However, this is the effect of looking at the water in depth. The quality of the discharge yesterday was acceptable and was having minimal impact on the burn.
As dealing with construction site run-off is not an exact science it is possible that some further modifications/improvements will be required. Any such issues will be dealt with as they arise.
FCC Secretary 10/01/2017